Carburetion system for gaseous and liquid fuels



July 6, 1954 0. L. GARRETSON CARBURETION SYSTEM FOR GASEOUS AND LIQUID FUELS 2 Sheets-Sheet 1 Filed May 11, 1950 9% ms x m y 6, 1954 o. L. GARRETSON ,683,027

CARBURETION SYSTEM FOR GASEOUS AND LIQUID FUELS Filed May 11, 1950 2 Sheets-Sheet 2 66 IN V EN TOR.

OWZ/V Z. GAE/FETSO/V ATTOENEYS Patented July 6, 1954 UNITED STATES PATENT OFFICE CARBURETION SYSTEM FOR GASEOUS AND LIQUID FUELS Owen L. Garretson, RoswelLN. Mex.

Application May 11, 1950, Serial No. 161,419

8 Claims.

This invention relates .to carburetion systems for supplying gaseousfuel tointernal combustion engines, and is particularly directedto such systems that employ liquefied petroleum gas as a fuel, including improved pressure regulator and fuel delivery control'apparatus for regulating the flow of gaseous fuel to the carburetor. This invention is a continuation-in-part of my pending application,.Serial No. 106,022, filed July 21, 1949.

The principal object of thisinvention is to supply the optimum quantity of fuel to the engine at allspeeds and loads. .Other objects are to vary the pressure head on the fuel entering the mixing zone at agreater rate than the rate .of variation of the ressure head on the inspired air entering the mixing zone, so asto compensate for the diiferences in the specific heat characteristics of the fuel and the air; to vary the pressure head on the fuel relative to the pressure head on the air so as to enrich the-mixture ratio with increas ing throttle openings .to obtain maximum power at-full throttle opening and maximum economy at partial throttle openings; and tosupply the fuel to the air stream at a venturiand to balance out all unnecessary parts of the pressure dro in the intake system ahead of the venturi so as to prevent excessive enrichment of the mixture at high speeds or starving of the engine at low speeds, or other deleterious effects from the characteristics of the air cleaner as from changes in the pressure drop through the air cleaner in use.

A further object of this invention is to provide a gaseous fuel supply system that may be simply and easily installed on aconventional internal combustion engine equipped for operation on liquid fuel without interfering with the liquid fuel supply system, so that the fuel supply may be changed from liquid to gaseous and vice versa while the engine is in operation by simple valve controls. 7

Another object of theinvention is to protect the diaphragm of theregulator for gaseous fuel from overloads during-choking or backfiring ofthe engine.

Other objects willappear from the following detailed description of a preferred embodiment of the invention.

In the drawings: Fig. 1 is a fragmentary diagrammatic view,

partially in section, of the improved liquefied petroleum gas carburetionsystem constructed in accordance'with the present invention shown as applied to atractor;

Fig. 2 is avertical sectionview of the controller '2 taken on line 22 of Fig. 3 and looking in the direction of the arrows;

Fig; 3 is a top plan view of the controller shown in Fig. 2;

Fig. 4 is a sectional View taken on line 4-4 of Fig.2;

Fig. 5 is a top plan view of the nozzle valve and its connection to the diaphragm; and 7 Figs. 6-8 are fragmentary sectional views of typical main jet installations'for various styles of carburetor venturis.

Referring more particularly to the drawings, the device will be described as installed on a farm tractor. Applicant employs a simple, semi-universal cylinder and regulator mounting arranged so that a comparatively few models of the mounting may be installed on a comparatively large variety of tractors. The mounting of the conbracket assembly A in front of the radiator is a high pressure container or cylinder 1 0 for a liquefied fuel gas, such as propane, butane and the like, or a mixture thereof. The bracket A includes a platform for the base of the containerin the form of ring [3 which encircles the lower end portion of the container, there being spaced apart slats welded to the ring to support the cylinder.

In order to mount the platform on the tractor a pair of arms I 5 are attached to ring 13 and extend rearwardly for attachment to the tractor. To accomplish the latter, the rear portions of the arms l'5 are parallel and have holes for the reception of 'bolts ll by which they are mounted on forward end portions of the side beams 18 of the chassis of the tractor or on any suitable portion of the tractor chassis.

An upper clamping and steadying structure for the container is mounted upon the platform I 3 by braces 2!) which support a plate 2|. Extending from plate 2| are strap members 23 and a clamp device 24 holds the container in place, all as described in detail in my-aforesaid pending application.

As-seen in Fig. 1, in addition to the container l0, thefuel system comprises a shut-off valve'V,

a high-pressure regulatorH, a low-pressure regulator B, suitable; piping, and in some installations an equalizer E. The shut-off valve V has a hand wheel 42 for the opening and closing of the valve,

flexible hose 4 4 or the like connects the valve V with the high-pressure regulator H which is provided with a pressure gauge 46 and a screw 41 for adjusting the regulator to the pressure desired. The high-pressure regulator H is connected by a pipe 45 to a low-pressure regulator or controller, generally indicated at B. In a typical installation the high-pressure regulator H may be set to deliver gas at a pressure in the neighborhood of 5 to p. s. i. above atmospheric pressure.

The regulator B comprises upper and lower casing members and 50, respectively, the upper casing member 49 having an interiorly-threaded nipple 5i which removably receives the exteriorlythreaded, reduced end portion of a nut 52 for connection to the fuel supply. The main body portion of the nut 52 is interiorly-threaded to receive the threaded end of the pipe 48 and the reduced end portion of the nut is cone-shaped to form a nozzle, the inner end portion of which constitutes a valve seat 53.

A valve generally indicated at C is slidably received by a guideway 54 in the upper casing member 49. The valve 0 comprises a hollow sleeve 55, the outer end portion of which is interiorly-threaded to receive the threaded end portion of a plug 56. The outer end portion of the plug is of enlarged nut-like formation and has an outwardly opening cavity 51 for frictionally gripping a valve disk 58 formed of rubber or the like. A plurality of spaced guide vanes 55, 65, GI and 52 are mounted on the sleeve and extend longitudinally thereof. The inner and outer end portions of the vanes are beveled as indicated at 53 and 64. The inner end portion of the sleeve 55 is cut away as at and 66 between the vanes 59 and ED and BI and 62, respectively, to form a slot through which extends a bar 61 mounted in suitable openings in the inner end portion of the sleeve 55.

In order to open and close valve C, a lever 68 is pivotally mounted within the upper casing member 49 on a pivot pin 69 which is carried by a screw threaded stud 10. The stud H3 is received by a boss H formed on the inner face of the upper casing member 49 and a second boss 12 on the casing member 49 supports the free end of the pivot pin 59. The outer end of the lever 68 has an inverted, substantially V-shaped notch 13 for receiving the bar 51. The opposite end of the lever is pivoted in a slot 14 of a stem 15 by a pivot pin 16. The stem I5 is responsive to motion of the regulator diaphragm and is secured to the upper end of a spindle 11.

The upper and lower casing members 49 and 50 are provided with out-turned flanges l8 and 19, respectively, between which is clamped the peripheral edge portion of a diaphragm 80. Bolts and nuts 3| secure the casing members together. A plate 82 is mounted on the upper face of the diaphragm 85 and the plate and diaphragm are mounted upon the spindle 11. A washer 83 is received by the spindle l1 and is disposed between the stem 15 and the plate 82. With this arrangement, upward movement of the diaphragm from the position shown in Fig. 2 opens the valve C to admit gas from the nozzle 52 into the space between the casing member 49 and the diaphragm 80. The diaphragm is biased toward closed position sufficiently to maintain the valve C closed against the pressure delivered from the high pressure regulator II when the pressure is equal on the opposite sides of the diaphragm. In the illustrated arrangement, this biasing is effected by the weight of the diaphragm and its associated parts.

The regulator may, if desired, be provided with a relief valve through the diaphragm. For example, spindle l'l may be of square cross-section to provide clearance for relief flow and a relief valve disk 84 may be received by the spindle ii to engage the under face of the diaphragm 85. A coiled spring 85 may surround the lower end portion of the spindle W with its upper end engaging the under face of the valve disk 84. The lower end portion of the spring 85 may be received by a cup 86 mounted upon the spindle IT and retained by a nut 81.

The diaphragm Bil divides the regulator B into an upper or main gas-receiving and regulating compartment 89 and a lower or compensating air-receiving compartment 91]. The lower casing member 55 has a depending neck 91 on the lower end of which is threaded a bonnet cap 92 which is provided with an air inlet opening 53. A bonnet cap washer 9A is interposed between the bonnet cap 92 and the lower face of the neck 9!. A filter pad 95 of sisal fibre or the like is disposed within the neck 9| and rests upon a wire screen 96 which may be one-fourth inch mesh or any other desirable mesh. A second wire screen 9? rests upon the top surface of the filter pad 55 and a disk 88 is threadedly received by the upper portion of the neck 9| and is provided with an air inlet orifice 99.

The regulator has provision for two connections to the inlet system of the engine. The upper casing 49 has a screw threaded fuel outlet port Hi5 which receives a delivery pipe iei. In case the system is installed on a non-uniformly firing engine, a pipe T I52 is connected to pipe 01. A pipe 553 has one end connected to the T i532 (if present) and its opposite end connected to a fitting lil i. Fitting m4 is connected for communication with the Venturi throat H35 of the carburetor of the engine through the fuel jet [01. A valve screw I08 is mounted in the fitting [M for providing an adjustable restriction to the flow of gas from the pipe #53 into the carburetor.

The other connection of the regulator to the inlet system is to the lower casing member 55. Casing 50 has an air outlet port Hi9 which communicates with the air or compensating compartment 98' through a restricted orifice Ht, the effective area of which may be controlled by an adjustment screw llila. Port H19 receives one end portion of a pipe HI and if the engine is of the non-uniform firing variety, the opposite end of the pipe H! is connected to a pipe T H2. A pipe H3 leads from the T HE (if present) and communicates with the engine inlet in what may be termed an intermediate pressure zone I, which zone lies between the choke butterfly valve H4 and the venturi Hi5. An air intake pipe H40. is connected to the carburetor and in accordance with usual practice may lead to an air filter F or similar air cleaning device.

- The usual throttle valve 1 I5 is mounted adjacent the manifold end of the carburetor venturi for controlling the flow of the fuel mixture to the inlet manifold H6.

If the system just described is fitted to an engine having non-uniform firing, an equalizer generally indicated at E is supplied. It comprises upper and lower housings HI and H8, respectively, which are provided with outturned annular flanges I I9 and I20, respectively. A diaphragm 12! has its peripheral edge portion be inserted directly in the Venturi throat. Fig. 8 the carburetor intake'is in the form of an A nipple I24 conconnects the chamber I23 with the T coupling 1 I2 in the compensating air line. This structure is claimed in my copending application, Serial No. 161A18, filed May 11, 1950.

The connection of the jet ID! to the venturi I05 is diagrammatically shown in Fig. 1. ,In Fig.

6 a carburetor venturi 105a of the straigh* through type is shown wherein the jet Ifllais an elbow with its open end extending into the Venturi throat.

In Fig. 7 the Venturi throat Ifl'e'b'has a thickened wall and thejet Ifilb may In elbow and the jet I 070 is inserted upwardly :through the elbow wall and extends into the venturi I050 in the direction of fuel flow, much in the manner of the form shown in Fig. 6.

The gaseous fuel system may be installed on I a conventional engine having a liquid fuel car- 'buretor I06 provided with a float chamber I21 and a jet I26 for delivering liquid fuel from the float chamber to the throat of the venturi I 05,

without disturbing the existing connections between the various parts of the liquid fuel system and without appreciably modifying the operation of the engine on liquid fuel. Thus it is only necessary to close the shut-01f valve in the liquid fuel line leading to the carburetor and the gaseous fuel system can be placed in operation as soon as any remaining liquid fuel in the float chamber I21 has been consumed. Likewise, it is possible to change from gaseous to ing the cylinder valve V and opening the shut-off valve in the liquid fuel line. Since it is unnecsary to change the carburetor or any of the pipe connections, these changes can be made while the engine is running, if desired.

In operation of a typical installation, with main valve 42 open the high-pressure regulator H delivers gaseous fuel to the low-pressure regulator B at about 5 to p. s. i. above atmospheric pressure and the low-pressure regulator is so arranged that the weight of the diaphragm and i 06, the air intake pipe 4a and the air filter F.

The pressure drop produced by the flow resistance of the air filter F and 'the air intake pipe I Ma is not appreciable at cranking speeds. Thus, although the slight pressure drop that exists produces an air flow through the pipes H3 and III and the regulator chamber 90, the pressure in the regulator chamber '9!) remains substantially atmospheric. The pressure drop at the throat of the venturi I65, however, is transmitted through the pipes I03 and IUI to the regulator n.

chamber 89, and at cranking-speeds of the engine, is preferably made sufiicient to overcome the slightbias of the regulator holding the valve disk 58 against the seat 53. Thus fuel is 'adliquid fuel operation at any time by simply clostmitted to the regulator chamber 89 and-passes 7.5 I

chamber 90 remains a ithroughithepipes IIJI, I03 and I0! into the air stream-being drawn into the intake manifold I I6 in suificient quantity to produce an explosive mixture and start the engine.

If the engine is cold, or if for any reason the suction produced at cranking speed is insufficient to open the regulator valve, it is only necessary to close or partially close the choke valve H4.

Closing the choke produces additional suction in the carburetor which is applied equally to the pipes H3 and III. However, because of the opening of the chamber 90 of the regulator to atmosphere through the orifice 99 and the air filter the pressure in the chamber 90 is at all times higher than the pressure in the Zone I in the manifold applied to the pipe H3 in a proportion determined by the relative sizes of the orifice 99 and the orifice Ht as adjusted by the valve I Ilia. Thus the suction created in the carburetor by the choke produces a lower pressure in the chamber 89 than in the chamber 90,

causing the diaphragm 90 to rise and open the valve 58. 1

During normal running of the engine the choke valve H4 is open. However, a pressure less than atmospheric exists in the intermediate zone I of the carburetor because of the pressure drop through the air intake pipe and the air cleaner which produces a suction in the pipes H3 and l I I and a flow of air into and through the regulator chamber 90. The additional pressure drop produced by the Venturi restriction IE5 is added on to this pressure drop in the intermediate section I of the carburetor and is applied to the jet I07. Thus as the throttle H5 is opened and the air speed through the carburetor increases an increasing pressure drop is applied to the pipe H3 and the same pressure drop, plus a further pressure drop produced by the Venturi restriction and increasing at a faster rate is applied to the jet I91. Only a slight pressure differential between the chambers 89 and 20 is required to overcome the bias of the regulator valve and open the valve 53 to admit gaseous fuel from the high pressure regulator H into the regulator pressure in the .Venturi throat I05 decreases with increased throttle openings and consequent increased rates of air flow, the pressure drop between the chamber 39 and the discharge end of the jet I01, most of which occurs at the valve I08, increases while the pressure in the regulator slight amount higher than the pressure in the regulator chamber 89, just suflicientto overcome the bias of the regulator valve towards closed position.

The pressure head on the air entering the throat of the venturi. which determines the amount of air which iiows into the Venturi throat and is mixed with the fuel entethrough the jet H l is not the difference between atmospheric pressure and the pressure in the Venturi throat, but on the contrary is the difference between the pressure in the zone I at the entrance to the venturi and the pressure in the throat. The pressure in zone I is always less than atmospheric pressure when the engine is running, and decreases as the throttl opening increases. Thus if thepressure in the regulator chamber 95 were made-equal to the pressure in zone I at all throttle openings, the pressure head applied to the fuel wouldbe equal to that applied tothe inspired air at all throttle openings. However, due to the fact that the ratio of the specific heat of air at constant pressure to its specific heat at constant volume is greater than the corresponding ratio for liquefied petroleum gas, such as propane and butane and mixtures thereof, the mixture would become slightly leaner with increased flow if exactly balanced pressures were maintained, since the weight of fuel inspired. would not increase in constant ratio with the weight of air inspired. Thus to maintain a constant mixture ratio it is necessary to increase the pressure head on the fuel at a rate slightl greater than the rate at which the pressure head on the air entering the Venturi throat increases with increasing throttle openings.

In addition, it is desirable from the standpoint of fuel economy to enrich the mixture slightly to the ratio for maximum power at full throttle opening, and lean it to the mixture ratio producing maximum economy at small throttle openmgs.

In the embodiment disclosed, these results are accomplished by proportioning the orifices 99 and Hi through which the intermediate zone I is connected to the atmosphere, so as to produce between the orifices a pressure drop which is a substantially constant fraction of the pressure drop existing in the intermediate zone I, and applying this pressure between the orifices to the regulator chamber 9!]. The ratio between the pressure applied to the chamber 96 and the pressure existing in the intermediate zone I is selected so that the pressure head applied to the fuel increases with increased throttle opening just sufficiently more than the pressure head applied to the inspired air to counteract the leaning effect of the specific heat characteristics and to richen the mixture ratio from the maximum economy ratio at small throttle openings to the maximum power ratio at full throttle opening.

A further increase in the pressure head on the fuel at high rates of flow is obtained with the regulator valve illustrated. When the valve 58 is closed, the gaseous fuel from the high pressure regulator I-I exerts a force tending to open the valve 553 which is equal to the unit pressure of the gas multiplied by the area of the nozzle opening 53. When the valve 58 is opened a substantial amount to permit high rates of fuel fiow, the

restricted area between the flutes 6B, 6! and 62 produces a. pressure drop which is applied to the plunger C, which has a greater cross-sectional area than the nozzle opening 53. Thus as flow increases, the pressure in chamber 85 increases wtih respect to the pressure in chamber 96. This arrangement not only eliminates any tendency for the delivery pressure to decrease with respect to the control pressure in chamber 99 with increasing flows, but may also be utilized to produce any desired part of the increase of the pressure head on the fuel with respect to the pressure head on the inspired air with increasing flows, so as to enrich the mixture at full throttle opening.

In one practical embodiment of the invention which has been found to operate satisfactorily the orifice HE! is made /8 of an inch in diameter and the orifice 99 is made ie of an inch in diameter. With this arrangement about of the pressure drop occurring in the intermediate zone I of the carburetor is applied to the chamber 95!. In other words about A; of the pressure drop produced by the intake pipe and air cleaner, which is applied both to the pipe H3 and the jet Hi1, is balanced out between the two sides of the regulator diaphragm 8d, the remaining being used to produce an increasing rate of fuel flow with respect to the rate of air flow as the throttle is opened. Any desired proportion of the ressure drop may be utilized, and in the preferred embodiment the orifice I it is made adjustable by the needle valve Hlia. Partially closing the valve Hila so as to reduce the size of the orifice H0 reduces the fraction of the pressure drop in the zone I which exists between the oriflees and thus increases the pressure in the chamber 90.

The valve N58 is adjusted for the particular engine on which the fuel system is used to determine the amount of fuel admitted to the carburetor by a given pressure head between the throat of the venturi and the regulator chamber 89. When the correct setting for this valve has been determined it is unnecessary to change the valve in normal operation. Preferably, the valve 19% is located near the carburetor and the lines HH and 1&3 are made of sufficient size so that most of the pressure drop between the regulator chamber 89 and the outlet of the jet it? occurs at the valve H38. Thus when the throttle opening is suddenly increased gaseous fuel is available close to the carburetor at a relatively high pressure, thereby minimizing delay in the response of the fuel system to the increased throttle opening. At idling speeds no additional enrichment is required with gaseous fuels, such as liquefied petroleum gas, since the mixture delivered to the cylinders is substantially uniform and it is not necessary to enrich the mixture to compensate for unequal distribution to the different cylinders of an engine as is usually necessary in using liquid fuel in multi-cylinder engines. With the present arrangement, as the throttle opening diminishes the pressure in the intermediate zone I approaches atmospheric and the pressure in the regulator chamber as also approaches atmospheric from its initiall higher value. Thus the effect of the corrective action of the pipes iii and H3 and the orifices as and Iii) levels off at idling speeds and becomes negligible at cranking speeds so that the mixture ratio remains substantially constant through the idling speed range. V

The equalizer E is intended primarily for use with engines having two or more cylinders with an uneven firing order but is also useful in connection with any type of engine to provide additional fuel for rapid acceleration an avoid excessive enrichment in rapid deceleration, and to permit the use of a less sensitive regulator. Ihe chamber I22 of the equalizer is preferably con nected to the fuel line sen between the regulator chamber 89 and the fuel valve act, and the chamber N23 is preferably connected to pipes iii and I i3 between the zone I of the carburetor and the orifice H0. Thus during normal running of the engine while air is being inspired through the carburetor the pressure in the chamber M23 is substantially equal to the pressure in the zone I and is less than the pressure in the chamber of the regulator. The pressure in chamber 9% exceeds the pressure in the chamber only by the slight amount required to overcome the bias of the regulator towards closed position, which is less than the difference in pressure between t1 e regulator chamber to and the intermediate zone I during such normal running. Thus the pressure in the chamber I22 exceeds the pressure in the chamber 123, forcing the diaphragm i2i into the chamber E23 and filling the chamber 22 with gaseous fuel. However, when suction-is beginning, as at the beginning ofv an intake stroke in.

value than the pressure in the chamber I22. and. the gaseous fuel contained therein is delivered.

to the pipe I03 until the incoming fuel from the regulator chamber 89 resulting from the opening or increased opening of-the regulator valve again. raises the pressure in the chamber I22 and. pipe I03 to its normal running value.

This system provides for ready-conversion'to liquefied petroleum gas by drilling two. holes in the standard carburetor and'connecting the fuel and air pipes therewith. No special carburetor: is required. There is no change required in'the air cleaner connection, choke control, hand throttle control, governor control, or othermodifications which consume so much time wheninstalling other systems, yet the operatingcharacteristics are better than thosev obtained by more complex installations. At the same time, once the system is installed it is not necessary to remove or alter it if for any reason it is desired to operate the engine on liquid fuel, it being only necessary to close the cylinder valve 42 and open the valve in the liquid fuel line.

The fact that both the fuel line connected to the jet l! and the air balance line connected to the zone I of the carburetor are locateddownstream from the choke valve H4 hastheaddi tional advantage of preventing the application of excessive pressure to the diaphragm 80 of the regulator or the diaphragm l2| of the equalizer E, where the latter is used, since suction produced by choking or pressure produced by back-firing are substantially balanced on opposite sides of the diaphragm l2! and are or more balanced on opposite sides of the diaphragm 80.

Bracket A is arranged so that the container [ii is disposed on the tractor in heat transfer relation with respect to the engine radiator. Thus, heat is transferred from the radiator to the container to assist in supplying the heat of vaporization absorbed during the evaporation of the liquefied petroleum gas. In addition, the container chills the air which flows through the radi ator to increase the efficiency of the engine cooling system.

Having completed a detailed description of my invention so that others skilled in the art may understand and practice the same, it will be apparent that other forms thereof may be provided without departing from the essence of the invention as defined in the appended claims.

What is claimed is:

l. A regulator for a gaseous fuel system for an internal combustion engine having an intake conduit open to atmosphere, a venturi, and a throttle downstream from the venturi, including a fuel receiving chamber and an air receiving chamber, a movable pressure responsive element separating said chambers, a valve for admitting fuel to said fuel receiving chamber, means operated by movement of said pressure responsive element for opening and closing said valve, whereby the position of said valve is determined by the relative pressures in said fuel chamber and said air chamber, a conduit for connecting said fuel receiving chamber to the venturi in the intake of an internal combustion engine, a duct for connecting said air receiving chamber to the intake of such engine upstream of said venturi, a first restricted orifice connecting said duct to atmosv10 phere, and a second restricted orifice in said .duct betweensaidfirst orifice and the engine intake,

the ratio of'areas of'said orifices being arranged" so that the pressure head applied to the fuel relative to pressure ofthe venturi increases with increased throttle opening sufiiciently to provide proper fuel air mixtures at allthrottle settings;

2. A regulator for a gaseous fuel system for an internal combustion engine having an intake conduit open to atmosphere, a venturi, and a throttle downstream from'the venturi, including a fuel receiving chamber and an air receiving chamber, a movable pressure'responsive element separating saidchambers; a valve for admitting fuel to said fuel receivingchamber, means operated by movement of said'pressure responsive elementfor opening andclosing said'valve, whereby-the position of said valve is determined by the relative pressures in said fuel chamber and said air chamber, a conduit for connecting said fuelre-- ceiving chamber to the venturi in the intake of an internal combustion engine, a duct for connecting said air receivingv chamber to the intake of such engine upstream of said venturi, a restricted orifice connecting said duct to atmosphere, and a second restricted orifice having a diameter about twice the diameter of said first orifice interposed in said duct between said first orifice and the engine intake.

3. An improved liquefied petroleum gas carburetion system for a tractor or the like comprising, a controller having a diaphragm therein for dividing said controller into two chambers, a valved gas inlet passage to the first chamber and a separate independent outlet passage leading to the carburetor from the first chamber, an atmospheric air inlet to the second chamber and a separate independent outlet passage leading from the second chamber to the main air intake of the carburetor at a point downstream of the carburetor choke valve, and a lever mechanism connected to the diaphragm and adapted to open and close the gas inlet passage.

4. An improved liquefied petroleum gas carburetion system comprising a controller comprising a casing, a diaphragm in said casin for dividing it into a gas chamber and an atmospheric air chamber, said casing having a laterally disposed gas inlet passage opening into said gas chamber, a substantially horizontally disposed slide valve for controlling said passage, said casing having a gas outlet passage communicating with said gas chamber and the carburetor, said casing having an atmospheric air inlet opening into said air chamber, said casing having an atmospheric air outlet communicating with said air chamber and the main air intake of the carburetor at a point downstream of the choke valve, and a lever mechanism for opening and closing said valve and comprising a lever operatively connected to said diaphragm and substantially horizontally disposed and pivotally mounted in said casing, said lever having an operative connection with said valve, whereby movements of the diaphragm will actuate said lever to selectively open and close said valve.

5. An improved liquefied petroleum gas carburetion system as claimed in claim 4 characterized by the fact that said operative connection between the diaphragm and the lever comprises a spindle, and that the connection between the lever and the valve comprises a notch in the lever and a bar on the valve.

6. An improved liquefied petroleum gas carburetion system for a tractor or the like comprising a controller having upper and lower casin members, a diaphragm clamped between said members for dividing said controller into a gas chamber and an air chamber, a valved gas inlet passage to the gas chamber, an outlet passage leading to the carburetor from the gas chamher, an atmospheric air inlet to the air chamber, an outlet passage leading from the air chamber to the main air intake of the carburetor at a point downstream of the choke valve, and a lever mechanism connected to the diaphragm and adapted to open and close the gas inlet passage.

7. An improved liquefied petroleum gas carburetion system for a tractor or the like comprising a controller having upper and lower casing members, a diaphragm clamped between said members for dividing said controlled into a gas chamber and an air chamber, a valved gas inlet passage to the gas chamber, an outlet passage leading to the carburetor from the gas chamher, an atmospheric air inlet to the air chamber, an outlet passage leading from the air chamber to the main air intake of the carburetor at a point downstream of the choke valve, and means connected. to the diaphragm and adapted to open and close the gas inlet passage.

8. A carburetion system as defined in claim 7 characterized by a shut-ofi valve in said gas carburetion system, and a liquid fuel jet opening into said carburetor.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,169,487 Ensign Aug. 15, 1939 2,315,881 Thomas Apr. 6, 1943 2,343,765 Garretson Mar. 7, 1944 2,346,763 Jones Apr. 18, 1944 ,391,410 Gerson Dec. 25, 1945 2,520,120 Bodine Aug. 29, 1950 

